HYBRID INTRA-CELL / INTER-CELL REMOTE UNIT ANTENNA BONDING IN MULTIPLE-INPUT, MULTIPLE-OUTPUT (MIMO) DISTRIBUTED ANTENNA SYSTEMS (DASs)

ABSTRACT

Hybrid intra-cell/inter-cell remote unit antenna bonding in multiple-input, multiple-output (MIMO) distributed antenna systems (DASs), and related components, systems, and methods. The MIMO DASs are capable of supporting distributed MIMO communications with client devices. To provide enhanced MIMO coverage areas, hybrid intra-cell/inter-cell remote unit antenna bonding is employed. For example, if a client device has acceptable MIMO communications signal quality with MIMO antennas within a single remote unit, intra-cell bonding of the MIMO antennas can be employed to provide MIMO coverage for MIMO communications, which may avoid power imbalance issues that would result with inter-cell bonded MIMO antennas. However, if a client device has acceptable MIMO communications signal quality with MIMO antennas in a separate, neighboring remote unit(s), inter-cell bonding of the MIMO antennas can be employed to provide MIMO coverage for MIMO communications.

PRIORITY APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/721,357, filed May 26, 2015, which is a continuation of InternationalApplication No. PCT/US13/70489, filed on Nov. 18, 2013, which claims thebenefit of priority to U.S. Provisional Application No. 61/731,043,filed on Nov. 29, 2012, all of which are incorporated herein byreference in their entireties.

BACKGROUND

Field of the Disclosure

The technology of the present disclosure relates to distributed antennasystems that are capable of distributing wireless radio-frequency (RF)communications services over wired communications mediums.

Technical Background

Wireless communication is rapidly growing, with ever-increasing demandsfor high-speed mobile data communication. As an example, “wirelessfidelity” or “WiFi” systems and wireless local area networks (WLANs) arebeing deployed in many different types of areas (coffee shops, airports,libraries, etc.). Wireless communication systems communicate withwireless devices called “clients,” which must reside within the wirelessrange or “cell coverage area” in order to communicate with the accesspoint device.

One approach to deploying a wireless communication system involves theuse of “picocells.” Picocells are radio frequency (RF) coverage areashaving a radius in the range from about a few meters up to about twenty(20) meters. Picocells can be provided to provide a number of differentservices (e.g., WLAN, voice, radio frequency identification (RFID)tracking, temperature and/or light control, etc.). Because a picocellcovers a small area, there are typically only a few users (clients) perpicocell. Picocells also allow for selective wireless coverage in smallregions that otherwise would have poor signal strength when covered bylarger cells created by conventional base stations.

In conventional wireless systems, as illustrated in FIG. 1, picocellcoverage areas 10 in a distributed communications system 12 are createdby and centered on remote antenna units 14 connected to a head-endequipment 16 (e.g., a head-end controller or head-end unit). The remoteantenna units 14 receive wireless communications services from thehead-end equipment 16 over a communications medium 17 to be distributedin their coverage area 10. The remote antenna unit includes informationprocessing electronics, an RF transmitter/receiver, and an antenna 18operably connected to the RF transmitter/receiver to wireless distributethe wireless communication services to wireless client devices 20 withinthe coverage area 10. The size of a coverage area 10 is determined bythe amount of RF power transmitted by the remote antenna unit 14,receiver sensitivity, antenna gain and the RF environment, as well as bythe RF transmitter/receiver sensitivity of the client device 20. Clientdevices 20 usually have a fixed RF receiver sensitivity, so that theproperties of the remote antenna unit 14 mainly determine the picocellcoverage area size.

One problem that can exist with wireless communication systems,including the system 10 in FIG. 1, is the multi-path (fading) nature ofsignal propagation. This simply means that local maxima and minima ofdesired signals can exist over a picocell coverage area. A receiverantenna located at a maximum location will have better performance orsignal-to-noise ratio (SNR) than a receiver antenna located in a minimumposition. Signal processing techniques can be employed to improve theSNR of wireless data transmission in such wireless communicationsystems. For example, spatial diversity can be utilized in instancesinvolving many access points. Other signal processing techniques includeMultiple Input/Multiple Output (MIMO) techniques for increasing bitrates or beam forming for SNR, or wireless distance improvement. MIMO isthe use of multiple antennas at both a transmitter and receiver toincrease data throughput and link range without additional bandwidth orincreased transmit power. MIMO technology can be employed in distributedantenna systems (DAS) to increase the bandwidth up to twice the nominalbandwidth.

Even with the potential doubling of bandwidth in a distributedcommunication system employing MIMO technology, a client device muststill be within range of two MIMO antennas to realize the full benefitsof increased bandwidth of MIMO technology. Ensuring uniform MIMOcoverage may be particularly important for newer cellular standards,such as Long Term Evolution (LTE), where increased bandwidthrequirements are expected by users of client devices in all coverageareas.

Current MIMO distributed communication systems may not provide uniformcoverage areas, particularly in the edges of coverage cells. In thisregard to further illustrate this problem, FIG. 2A illustrates a portionof exemplary MIMO coverage areas 10 in the distributed communicationssystem 12 in FIG. 1. The MIMO coverage areas 10 in FIG. 2A are providedby two remote antenna units 14(1), 14(2), which are separated at adistance D₁ from each other. Each remote antenna unit 14(1), 14(2) hastwo antennas 18(1)(1), 18(1)(2) and 18(2)(1), 18(2)(2) respectively. Theantenna pairs 18(1)(1), 18(1)(2) and 18(2)(1), 18(2)(2) are each capableof being configured to be intra-cell bonded together to operate in MIMOconfiguration. By intra-cell remote unit antenna bonding, it is meantthat an antenna pair 18 in a particular remote antenna unit 14 are bothinvolved in communications with a particular client device to provideMIMO communications. The first remote antenna unit 14(1) provides afirst MIMO coverage area 22(1) using antennas 18(1)(1) and 18(1)(2). Thesecond remote antenna unit 14(2) provides a second MIMO coverage area22(2) using antennas 18(2)(1) and 18(2)(2). A wireless client device(not shown) located within the first MIMO coverage area 22(1) willreceive MIMO services by remote antenna unit 14(1), because the clientdevice will be in range of both antennas 18(1)(1) and 18(1)(2).Similarly, a client device located within the second MIMO coverage area22(2) will receive MIMO services by remote antenna unit 14(2), becausethe client device will be in range of both antennas 18(2)(1) and18(2)(2).

If a client device is located in a coverage area 24 outside or on theedge of the first and second MIMO coverage areas 22(1), 22(2), theclient device may still be in communication range of at least one of theantennas 18 of the remote antenna units 14(1), 14(2) to receivecommunications services. However, the client device will not be incommunication range with sufficient SNR ratio of both antenna pairs18(1)(1), 18(1)(2) or 18(2)(1), 18(2)(2) of a remote antenna unit 14(1),14(2), and thus will not receive MIMO communications services. FIG. 2Billustrates an exemplary graph 26 illustrating one relationship betweenantenna 18 separation of the remote antenna units 14(1), 14(2) and MIMOcondition number (CN) in decibels (dB). For a 700 MHz communicationsservice frequency, the allowed maximum antenna 18 separation isapproximately twenty (20) meters for MIMO capacity of six (6) bits persection per Hertz (s/Hz), assuming a condition number of 60 dBillustrated as line 28. At a 2.6 GHz communications service frequency,the allowed maximum antenna 18 separation is approximately ten (10)meters for MIMO capacity of six (6) bits per section per Hertz (s/Hz),assuming a condition number of 60 dB.

An increased number of remote antenna units could be provided to reducethe maximum separations between MIMO antennas, and thus reduce oreliminate non-MIMO coverage areas. However, providing an increasednumber of remote antenna units in a distributed communications systemincreases system cost. Also, providing an increased number of remoteantenna units can add additional complexity and associated cost byrequiring support of a greater number of remote antenna units in thedistributed communications systems.

SUMMARY OF THE DETAILED DESCRIPTION

Embodiments disclosed herein include hybrid intra-cell/inter-cell remoteunit antenna bonding in multiple-input, multiple-output (MIMO)distributed antenna systems (DASs). Related components, systems, andmethods are also disclosed. In certain embodiments disclosed herein,MIMO distributed antenna systems are provided that are capable ofsupporting distributed MIMO communications with client devices inwireless communication range of remote units. MIMO communicationsinvolve use of multiple MIMO antennas at both a transmitter and receiverto increase data throughput and link range to increase bandwidth up totwice nominal bandwidth.

To provide enhanced MIMO coverage areas in MIMO DASs, hybridintra-cell/inter-cell remote unit antenna bonding is employed.Intra-cell remote unit antenna bonding is the involvement or bonding ofMIMO antennas within a single remote unit to provide MIMO communicationswith a client device. Inter-cell remote unit antenna bonding is theinvolvement or bonding of MIMO antennas between separate, neighboringremote units to provide MIMO communications with a client device. Forexample, if a client device has acceptable and/or higher MIMOcommunications signal quality with MIMO antennas within a single remoteunit, intra-cell bonding of the MIMO antennas can be employed for MIMOcommunications to provide MIMO coverage to avoid power imbalance issuesthat may result with inter-cell bonded remote unit antennas. However, asanother example, if a client device has acceptable and/or higher MIMOcommunications signal quality with MIMO antennas with one or moreneighboring remote units, inter-cell bonding of the MIMO antennas can beemployed for MIMO communications to provide MIMO coverage that may nototherwise be available from intra-cell bonding. More sparse and lowercost remote unit deployments can thus provide substantially uniformhigh-capacity MIMO DAS coverage.

In one embodiment, a method of providing hybrid intra-cell/inter-cellremote unit antenna bonding for multiple-input, multiple-output (MIMO)communications with a client device in a MIMO DAS comprises configuringintra-cell antenna bonding for MIMO communications for a client deviceat a first remote unit in a MIMO DAS. The method also comprisesreceiving intra-cell antenna bonded MIMO communications signals from theclient device at the first remote unit, and determining if the receivedintra-cell antenna bonded MIMO communications signals at the firstremote unit exceed a threshold MIMO communications signal quality. Ifthe received intra-cell antenna bonded MIMO communications signals atthe first remote unit do not exceed the threshold MIMO communicationssignal quality, the method further comprises receiving MIMOcommunications signals from the client device from at least oneneighboring remote unit to the first remote unit, and determining if thereceived MIMO communications signals at the at least one neighboringremote unit exceed a threshold MIMO communications signal quality. Ifthe received MIMO communications signals at the at least one neighboringremote unit exceed the threshold MIMO communications signal quality, themethod also comprises configuring inter-cell antenna bonding for MIMOcommunications for the client device in the at least one neighboringremote unit.

In another embodiment, a controller for providing hybridintra-cell/inter-cell remote unit antenna bonding for multiple-input,multiple-output (MIMO) communications with a client device in a MIMO DASis configured to configure intra-cell antenna bonding for MIMOcommunications for a client device at a first remote unit in a MIMO DAS.The controller is also configured to receive intra-cell antenna bondedMIMO communications signals from the client device at the first remoteunit, and to determine if the received intra-cell antenna bonded MIMOcommunications signals at the first remote unit exceed a threshold MIMOcommunications signal quality. If the received intra-cell antenna bondedMIMO communications signals at the first remote unit do not exceed thethreshold MIMO communications signal quality, the controller isconfigured to receive MIMO communications signals from the client devicefrom at least one neighboring remote unit to the first remote unit, anddetermine if the received MIMO communications signals at the at leastone neighboring remote unit from the client device exceed a thresholdMIMO communications signal quality. If the received MIMO communicationssignals at the at least one neighboring remote unit exceed the thresholdMIMO communications signal quality, the controller is configured toconfigure inter-cell antenna bonding for MIMO communications for theclient device in the at least one neighboring remote unit.

In another embodiment, a computer-readable medium having instructionsfor causing a computer to execute a method of providing hybridintra-cell/inter-cell remote unit antenna bonding for multiple-input,multiple-output (MIMO) communications with a client device in a MIMO DASis provided. The instructions cause the computer to configure intra-cellantenna bonding for MIMO communications for a client device at a firstremote unit in a MIMO DAS, to receive intra-cell antenna bonded MIMOcommunications signals from the client device at the first remote unit,and cause the computer to determine if the received intra-cell antennabonded MIMO communications signals at the first remote unit exceed athreshold MIMO communications signal quality. If the received intra-cellantenna bonded MIMO communications signals at the first remote unit donot exceed the threshold MIMO communications signal quality, theinstructions also cause the computer to receive MIMO communicationssignals from the client device from at least one neighboring remote unitto the first remote unit, and determine if the received MIMOcommunications signals at the at least one neighboring remote unit fromthe client device exceed a threshold MIMO communications signal quality.If the received MIMO communications signals at the at least oneneighboring remote unit exceed the threshold MIMO communications signalquality, the instructions also cause the computer to configureinter-cell antenna bonding for MIMO communications for the client devicein the at least one neighboring remote unit.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part, will be readily apparent tothose skilled in the art from that description or recognized bypracticing the embodiments as described herein, including the detaileddescription that follows, the claims, as well as the appended drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of a distributed communications systemcapable of distributing wireless communications services to clientdevices.

FIG. 2A illustrates a portion of MIMO coverage areas and non-MIMOcoverage areas in a distributed communications system employing MIMOtechnology and intra-cell remote antenna unit bonding.

FIG. 2B is a graph illustrating one relationship between antennaseparation of the remote units in FIG. 2A and MIMO condition number (CN)in decibels (dB).

FIG. 3A is a schematic diagram of a MIMO distributed antenna systemconfigured to support MIMO communications services with client devices.

FIG. 3B is a schematic of a downlink path and uplink path and relatedcomponents of the remote unit in the MIMO DAS of FIG. 3A.

FIG. 4A illustrates a portion of MIMO coverage areas and non-MIMOcoverage areas for a given distance between cell bonded antennas fromadjacent remote units in the system in FIGS. 3A and 3B.

FIG. 4B illustrates a portion of MIMO coverage areas and non-MIMOcoverage areas for a more dense distribution of remote units to providea reduced distance between cell bonded antennas from neighboring remoteunits in the system in FIGS. 3A and 3B.

FIG. 4C is a graph illustrating an exemplary relationship betweenantenna separation of inter-cell bonded remote unit antennas in thesystem of FIGS. 3A and 3B and power imbalance threshold in decibels(dB).

FIG. 5 is a schematic diagram of hybrid intra-cell/inter-cell remoteunit antenna bonding provided in an adapted MIMO DAS of FIGS. 3A and 3B.

FIG. 6A is a flowchart illustrating a process for hybridintra-cell/inter-cell remote unit antenna bonding for client devices inthe system of FIG. 5.

FIG. 6B is a schematic diagram illustrating interfaces for the processin FIG. 6A for providing intra-cell and inter-cell remote unit antennabonding for MIMO communications in the system of FIG. 5.

FIG. 7 is a dynamic cell antenna bonding table used in the process inFIGS. 6A and 6B to dynamically store and identify intra-cell bondedremote unit antennas and inter-cell bonded remote unit antennas foractive client device communications in the system of FIG. 5.

FIG. 8 is a remote unit mapping table used in the process in FIGS. 6Aand 6B to identify and determine read MIMO communications signalqualities in neighboring remote units in the MIMO DAS of FIG. 5 fordetermining whether to retain a current remote unit antenna bonding modeor switch remote unit antenna bonding modes.

FIG. 9 is a graph of MIMO communications service performance in terms ofpercentage area of MIMO coverage for antenna separations for intra-cellbonded remote unit antennas, inter-cell bonded remote unit antennas, andhybrid intra-cell/inter-cell bonded remote unit antennas in the MIMOsystem of FIG. 5.

FIG. 10 is a schematic diagram of a generalized representation of acontroller.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, in which some, butnot all embodiments are shown. Whenever possible, like reference numberswill be used to refer to like components or parts.

Embodiments disclosed herein include hybrid intra-cell/inter-cell remoteunit antenna bonding that provide enhanced MIMO coverage in MIMOdistributed antenna systems (DASs). In certain embodiments, MIMO DASsare capable of supporting distributed MIMO communications with clientdevices in wireless range of remote units. MIMO communications involveuse of multiple MIMO antennas at both a transmitter and receiver toincrease data throughput and link range to increase bandwidth up totwice nominal bandwidth.

Intra-cell remote unit antenna bonding is the involvement or bonding ofMIMO antennas within a single remote unit to provide MIMO communicationswith a client device. Inter-cell remote unit antenna bonding is theinvolvement or bonding of MIMO antennas between separate, neighboringremote units to provide MIMO communications with a client device. Forexample, if a client device has acceptable and/or higher MIMOcommunications signal quality with MIMO antennas within a single remoteunit, intra-cell antenna bonding of the MIMO antennas can be employedfor MIMO communications to provide MIMO coverage to avoid powerimbalance issues that may result with inter-cell bonded remote unitantennas. However, if a client device has acceptable and/or higher MIMOcommunications signal quality with MIMO antennas with one or moreneighboring remote units, inter-cell antenna bonding of the MIMOantennas can provide MIMO coverage that may not otherwise be availablethrough intra-cell bonding.

Before discussing hybrid intra-cell/inter-cell remote unit antennabonding starting at FIG. 5, an exemplary MIMO DAS is described in regardto FIGS. 3A-4C. FIG. 3A is a schematic diagram of an exemplary MIMOoptical fiber-based distributed antenna system 30 (hereinafter referredto as “MIMO DAS 30”). The MIMO DAS 30 is configured to operate in MIMOconfiguration, which involves the use of multiple antennas at both atransmitter and receiver to improve communication performance. A centralunit 32 is provided that is configured to distribute downlinkcommunications signals to one or more remote units 34. FIG. 3A onlyillustrates one remote unit 34, but note that a plurality of remoteunits 34 is typically provided. The remote units 34 are configured towirelessly communicate the downlink communications signals to one ormore wireless client devices 36 (also referred to herein as “clientdevices 36”) that are in communication range of the remote unit 34. Theremote units 34 may also be referred to as “remote antenna units 34”because of their wireless transmission over antenna functionality. Theremote unit 34 is also configured to receive uplink communicationssignals from the client devices 36 to be distributed to the central unit32.

In this embodiment, an optical fiber communications medium 37 comprisingat least one downlink optical fiber 38D and at least one uplink opticalfiber 38U is provided to communicatively couple the central unit 32 tothe remote units 34. The central unit 32 is also configured to receiveuplink communications signals from the remote units 34 via the opticalfiber communications medium 37, although more specifically over the atleast one uplink optical fiber 38U. The client device 36 incommunication with the remote unit 34 can provide uplink communicationssignals to the remote unit 34 which are then distributed over theoptical fiber communications medium 37 to the central unit 32 to beprovided to a network or other source, such as a base station forexample.

With continuing reference to FIG. 3A, more detail will be discussedregarding the components of the central unit 32, the remote unit 34, andthe client device 36 and the distribution of downlink communicationssignals. The central unit 32 is configured to receive electricaldownlink MIMO communications signals 40D from outside the MIMO DAS 30 ina signal processor 42 and provide electrical uplink communicationssignals 40U, received from client devices 36, to other systems. Thesignal processor 42 may be configured to provide the electrical downlinkcommunications signals 40D to a mixer 44, which may be an IQ signalmixer in this example. The mixer 44 is configured to convert theelectrical downlink MIMO communications signals 40D to IQ signals. Themixer 44 is driven by a frequency signal 46 that is provided by a localoscillator 48. Frequency conversion is optional. In this embodiment, itis desired to up-convert the frequency of the electrical downlink MIMOcommunications signals 40D to a higher frequency to provide electricaldownlink MIMO communications signals 52D to provide for a greaterbandwidth capability before distributing the electrical downlink MIMOcommunications signals 52D to the remote units 34. For example, theup-conversion carrier frequency may be provided as an extremely highfrequency (e.g., approximately 30 GHz to 300 GHz).

With continuing reference to FIG. 3A, because the communication mediumbetween the central unit 32 and the remote unit 34 is the optical fibercommunications medium 37, the electrical downlink MIMO communicationssignals 52D are converted to optical signals by an electro-opticalconverter 54. The electro-optical converter 54 includes components toreceive a light wave 56 from a light source 58, such as a laser. Thelight wave 56 is modulated by the frequency oscillations in theelectrical downlink MIMO communications signals 52D to provide opticaldownlink MIMO communications signals 60D over the downlink optical fiber38D to the remote unit 34. The electro-optical converter 54 may beprovided so that the electrical downlink MIMO communications signals 52Dare provided as radio-over-fiber (RoF) communications signals.

With continuing reference to FIG. 3A, the optical downlink MIMOcommunications signals 60D are received by an optical bi-directionalamplifier 62, which is then provided to a MIMO splitter 64 in the remoteunit 34. The MIMO splitter 64 is provided so that the optical downlinkMIMO communications signals 60D can be split among two separate downlinkcommunication paths 66(1), 66(2) to be radiated over two separate MIMOantennas 68(1), 68(2) provided in two separate MIMO transmitters 70(1),70(2) configured in MIMO configuration. The MIMO antennas 68(1), 68(2)are configured to be intra-cell bonded, meaning that both MIMO antennas68(1), 68(2) within a given remote unit 34 are designed to be involvedin communications with a particular client device 36 to provide MIMOcommunications with the particular client device 36. The MIMO splitter64 in the remote unit 34 is an optical splitter since the receivedoptical downlink MIMO communications signals 60D are optical signals. Ineach downlink communication path 66(1), 66(2), downlinkoptical-to-electrical converters 72D(1), 72D(2) are provided to convertthe optical downlink MIMO communications signals 60D to electricaldownlink MIMO communications signals 74D(1), 74D(2). The uplink path ofthe communications paths 66(1), 66(2) in the remote unit 34 isillustrated in FIG. 3B. As illustrated in FIG. 3B, uplinkelectrical-to-optical converters 72U(1), 72U(2) are also provided in theremote unit 34 to convert electrical uplink MIMO communications signals74U(1), 74U(2) received from the client device 36 to optical uplink MIMOcommunications signals 60U(1), 60U(2) to be communicated over the uplinkoptical fiber 38U(1), 38U(2) to the central unit 32.

With reference back to FIG. 3A, the client device 36 includes two MIMOreceivers 76(1), 76(2) that include MIMO receiver antennas 78(1), 78(2)also configured in MIMO configuration. The MIMO receiver antennas 78(1),78(2) are configured to receive the electrical downlink MIMOcommunications signals 80D(1), 80D(2) wirelessly from the remote unit34. Mixers 82(1), 82(2) are provided and coupled to the MIMO receiverantennas 78(1), 78(2) in the client device 36 to provide frequencyconversion of the electrical downlink MIMO communications signals80D(1), 80D(2). A local oscillator 84 is provided that is configured toprovide oscillation signals 86(1), 86(2) to the mixers 82(1), 82(2),respectively, for frequency conversion. In this embodiment, theelectrical downlink MIMO communications signals 80D(1), 80D(2) are downconverted back to their native frequency as received by the central unit32. The down converted electrical downlink MIMO communications signals80D(1), 80D(2) are then provided to a signal analyzer 88 in the clientdevice 36 for any processing desired.

Even with the potential doubling of bandwidth in the MIMO DAS 30 inFIGS. 3A and 3B, a client device 36 must still be within range of twoMIMO antennas 68(1), 68(2) of a remote unit 34 to properly operate inMIMO configuration with increased bandwidth. Otherwise, the fullbenefits of increased bandwidth of MIMO technology provided in the MIMODAS 30 may not be realized. Ensuring uniform MIMO coverage in coverageareas of the DAS 30 may be particularly important for newer cellularstandards, such as Long Term Evolution (LTE), where increased bandwidthrequirements are expected by users of client devices 36 in all coverageareas. Thus, it is desired to provide uniform coverage areas in the MIMODAS 30, particularly in the edges of MIMO coverage cells.

As discussed above with regard to FIGS. 2A and 2B, providing intra-cellremote unit antenna bonding in the DAS 30 in FIGS. 3A and 3B may stillprovide non-uniform MIMO coverage areas unless a high density of remoteunits 34 are provided, thereby increasing cost and complexity. FIG. 4Aillustrates a portion of exemplary coverage areas 90 in the MIMO DAS 30of FIGS. 3A and 3B when inter-cell remote unit antenna bonding isprovided, as opposed to intra-cell antenna bonding. Inter-cell antennabonding means that one MIMO antenna from one remote unit is selected tobe paired with another antenna in a separate, neighboring remote unit tobe involved with MIMO communication with a particular client device. Inthis manner, if a client device is located between the neighboringremote units such that the client device has acceptable and/or higherMIMO communications signal quality with two MIMO antennas provided inseparate, neighboring remote units than a particular MIMO antenna pairin a single remote unit, the client device can enjoy the increased MIMOcommunication gain levels with inter-cell bonded MIMO antennas overintra-cell remote unit antenna bonding.

Referring to FIG. 4A, the coverage areas 90 are provided by two remoteunits 34(1), 34(2) separated at a distance D₂. Only one of the MIMOantennas 68(1), 68(2) for each remote unit 34(1), 34(2) is illustrated,although there are two MIMO antennas 68 provided in each remote unit34(1), 34(2). In this embodiment, to avoid non-uniform coverage areasfor client devices 36, inter-cell antenna bonding of the MIMO antennas68(1), 68(2) from the separate, neighboring remote units 34(1), 34(2) isprovided. The inter-cell antenna bonding of the MIMO antennas 68(1),68(2) provides a MIMO coverage area 92 as illustrated in FIG. 4A.However, providing this inter-cell bonding of the MIMO antennas 68(1),68(2) in FIG. 4A will provide non-MIMO coverage areas 94(1), 94(2) as aresult of power imbalance that occurs when the client device 36 islocated close to one of the MIMO antennas 68(1), 68(2), and locatedfarther away from the other inter-cell bonded MIMO antenna 68(2), 68(1),respectively.

This power imbalance issue with inter-cell antenna bonding between theremote units 34(1), 34(2) in FIG. 4A can be reduced or minimized byproviding the remote units 34(1), 34(2) closer to each other, as shownin FIG. 4B. As illustrated in FIG. 4B, the MIMO antennas 68(1), 68(2) ofthe remote units 34(1), 34(2) are separated at a distance D₃ from eachother, which is less than D₂ in FIG. 4A. This configuration increasesthe MIMO coverage area 92′ and reduces the non-MIMO coverage areas94(1)′, 94(2)′, as illustrated in FIG. 4B. However, there are stillnon-MIMO coverage areas 94(1)′, 94(2)′ provided, which will reduce ornot allow MIMO communications when client devices 36 are located inthese non-MIMO coverage areas 94(1)′, 94(2)′. The remote unit 34(1),34(2) configuration in FIG. 4B is also more expensive, because a greaternumber of remote units 34 are required to provide communicationscoverage in the DAS 30 for a given desired coverage area.

FIG. 4C further illustrates the power imbalance issues as a result ofinter-cell bonded remote units 34. FIG. 4C is an exemplary graph 96illustrating an exemplary relationship between maximum antennaseparation of inter-cell bonded remote units 34 in the MIMO DAS 30 ofFIGS. 3A and 3B and power imbalance threshold in decibels (dB) at a 700MHz communications frequency. As illustrated in FIG. 4C, for a maximumpower imbalance of 12 dB, the maximum MIMO antenna 68 separation cannotexceed 3 meters (m) for inter-cell antenna bonding, which is anextremely dense arrangement of remote units 34.

Hybrid intra-cell/inter-cell remote unit antenna bonding in MIMO DASsenhance MIMO coverage areas in MIMO distributed antenna systems. If aclient device has acceptable and/or higher MIMO communications signalquality with MIMO antennas within a single remote unit, intra-cellbonding of the MIMO antennas can be employed for MIMO communications toprovide MIMO coverage to avoid power imbalance issues that may resultwith intra-cell bonded remote units. MIMO communications signal qualityare a function of distance between a client device and MIMO antennas andquality degrades with distance due to degraded signal strength withdistance. However, if a client device has acceptable and/or higher MIMOcommunications signal quality to MIMO antennas between at least oneseparate, neighboring remote unit, inter-cell bonding of the MIMOantennas can provide MIMO coverage that may not otherwise be availablethrough intra-cell bonding.

FIG. 5 is a schematic diagram of exemplary hybrid intra-cell/inter-cellremote unit antenna bonding provided in a MIMO DAS 30′ that is adaptedfrom the MIMO DAS 30 in FIGS. 3A and 3B. Common components between theMIMO DAS 30 and 30′ include common numbering in FIG. 5, and will not bere-described in detail.

As illustrated in FIG. 5, a plurality of remote units 34(1)-34(6) areprovided in the MIMO DAS 30′. Client devices 36(1)-36(3) are located inthe MIMO DAS 30′ and are configured to receive and transmit wirelessMIMO communications signals with the DAS 30′ via the remote units34(1)-34(6). The client device 36(1) is located closer to both MIMOantennas 68(1) in the remote unit 34(1) than any MIMO antennas 68 in anyseparate, neighboring remote unit 34(2) or 34(4). Thus, intra-cellremote unit antenna bonding is provided for the MIMO antennas 68(1)(1),68(1)(2) of remote unit 34(1) for MIMO communications with the clientdevice 36(1). In other words, MIMO antennas 68(1)(1), 68(1)(2) withinthe single remote unit 34(1) are configured to provide MIMOcommunications for the client device 36(1) as opposed to another MIMOantenna 68 from another neighboring remote unit 34 being configured toprovide the MIMO communications for client device 34(1). Similarly,intra-cell remote unit antenna bonding is provided for the MIMO antennas68(5)(1), 68(5)(2) of remote unit 34(5) for MIMO communications with theclient device 36(3).

With continuing reference to FIG. 5, inter-cell remote unit antennabonding is provided for MIMO communications for client device 36(2).Because the client device 36(2) has acceptable and/or higher MIMOcommunications signal quality (e.g., that exceeds a MIMO communicationssignal quality threshold) with MIMO antennas 68(4)(2) and 68(5)(1) thanMIMO antenna pairs 68(4)(1), 68(4)(2) or 68(5)(1), 68(5)(2), the DAS 30′is configured to inter-cell bond MIMO antennas 68(4)(2) and 68(5)(1) forMIMO communications with client device 36(2).

FIG. 6A is a flowchart illustrating an exemplary process for hybridintra-cell/inter-cell remote unit antenna bonding for client devices 36in the MIMO DAS 30′ of FIG. 5. FIG. 6B is a schematic diagramillustrating exemplary interfaces for the process in FIG. 6A forproviding intra-cell and intra-cell antenna bonding of remote units 34for MIMO communications with client devices 36 in the MIMO DAS 30′ ofFIG. 5. As will be discussed in more detail below, this processdetermines whether MIMO communication requested by client devices 36 inthe MIMO DAS 30′ should be provided using intra-cell or inter-cellremote unit antenna bonding and with which remote unit 34 or remoteunits 34. MIMO coverage can be provided to provide acceptable MIMOcommunications signal quality, if possible, based on both intra-cell andinter-cell antenna bonding without having to compromise between onlyproviding one or the other type of antenna bonding for MIMO coverage.The process is capable of dynamically adjusting whether intra-cell orinter-cell remote unit antenna bonding is employed for MIMOcommunications with a client device 36 based on the MIMO communicationssignal qualities of received MIMO communications signals by MIMOantennas 68 in the remote units 34 in the MIMO DAS 30′. It iscontemplated that the exemplary hybrid intra-cell/inter-cell remote unitantenna bonding process will be carried out by the central unit 32provided in the MIMO DAS 30′ in FIG. 5. However, the exemplary hybridintra-cell/inter-cell remote unit antenna bonding could also be carriedout in other components of the DAS 30′.

The process illustrated in FIGS. 6A and 6B is described with respect toone client device 36 and the central unit 32 performing the process.However, it should be noted that the process therein can be performed byother devices other than the central unit 32 and for all client devices36 communication with remote units 34 in the DAS 30′. The processinvolves a client device 36 communicating with MIMO antennas 68 of oneor more remote units 34 that are either intra-cell bonded or inter-cellbonded (block 100). For example, a new MIMO communication session with aclient device 36 may default to intra-cell antenna bonding with oneremote unit 34 as a non-limiting example. The identification of MIMOantennas 68 assigned or associated with MIMO communications withparticular client devices 36 can be stored in a dynamic cell antennabonding table 120, as illustrated in FIG. 7. The central unit 32 canconsult the dynamic cell antenna bonding table 120 to determine a cellbonding mode for remote units 34 and client devices 36, as well asstoring updated cell bonding modes when switched for remote units 34 andclient devices 36 according to the process in FIGS. 6A and 6B. Forexample, the cell bonding mode and the identification of remote units 34bonded to a client device 36 are used to determine which MIMO antennas68 are associated with MIMO communications with a particular clientdevice 36 so that the correct MIMO communications signals can beassociated with communications with a particular client device 36, suchas by the central unit 32 or a network coupled to the central unit 32.

With reference to FIG. 7, the dynamic cell antenna bonding table 120stores a client device identification 122 identifying client devices 36associated or bonded in MIMO communications with one or more remoteunits identifications 124 identifying remote unit 34. For example, asillustrated in FIG. 7, client device 1 36(1) is only associated withremote unit 1 34(1); thus client device 1 36(1) is intra-cell antennabonded with remote unit 1 34(1) as noted by the notation in the cellbonding mode 126 associated with client device 1 36(1). However, clientdevice 3 36(3) is inter-cell antenna bonded with remote unit 1 34(1) andremote unit 2 34(2), as noted by the notation in the cell bonding mode126 associated with client device 3 36(3). Client device 3 36(3) isassociated with remote units 1 34(1) and remote unit 34(2) in thedynamic cell antenna bonding table 120, as illustrated in FIG. 7.

With reference back to FIGS. 6A and 6B, the MIMO communications signalquality between the bonded MIMO antennas 68 and the client device 36 aremeasured and analyzed to determine if the MIMO communications signalshave acceptable signal quality (block 102). This step is performed todetermine if the current cell-bonding mode of a client device 36 issufficient to provide MIMO communications, examples of which have beenpreviously described. Signal strength may be used to determine the MIMOcommunications signal quality is of acceptable quality, as anon-limiting example. Further, this step may involve determining if theMIMO communications signal strength exceeds a predefined MIMOcommunications signal quality threshold. Other measuring and analysistechniques other than signal strength may also be employed to determineMIMO communications signal quality. The central unit 32 in thisembodiment is configured to receive signal quality information from theremote units 34(1)-34(M) via control channels 112(1)-112(M), asillustrated in FIG. 6B. If MIMO communications signal quality isacceptable or higher than current signal quality with a current cellbonding mode, the process repeats backs to block 100 by the clientdevice 36 continuing to perform MIMO communications in its current cellbonding mode with the associated remote units 34 as indicated in thedynamic cell antenna bonding table 120 (in FIG. 7) as long ascommunications signal quality with the current cell bondingconfiguration is acceptable (block 102). This step may involvedetermining if the MIMO communications signal strength exceeds apredefined MIMO communications signal quality threshold. An examplewhere communications signal quality with the current cell bondingconfiguration may no longer be acceptable is when the client device 34moves from its current location to another location in the MIMO DAS 30′in closer proximity to another remote unit(s) 34.

With continuing reference to FIGS. 6A and 6B, if the communicationssignal quality with the client device 36 is not of acceptable qualitywith the current cell bonding mode and antenna bonding configuration forthe client device 36 (block 102), the process involves determining ofthe cell bonding mode and antenna bonding configuration can be switchedto maintain acceptable MIMO communications. The communications signalstrengths are read from neighboring remote units 34 to the remote unit34 current associated and bonded to the client device 36 (block 104).The dynamic cell-bonding table 120 in FIG. 7 can be consulted todetermine which remote units 34 are bonded to the client device 36. Aremote unit \ mapping table 130 in FIG. 8 can be employed to determinewhich remote units 34 are neighboring to the remote unit(s) 34 bonded tothe client device 36. The remote unit mapping table 130 in FIG. 8 storesa list of neighboring remote units 34 (132) with each remote unit 34identified by a remote unit identification 134 in the remote unit statictable 130. The remote unit mapping table 130 in FIG. 8 may be containremote unit mappings if the remote unit mapping table 130 is configuredat setup or initialization of the MIMO DAS 30′ depending on theconfiguration and layout of the remote units 34.

With continuing reference to FIGS. 6A and 6B, after the neighboringremote units 34 are identified, the signal quality of MIMOcommunications signals between the neighboring remote units 34 and theclient device 36 are measured and analyzed to determine if of acceptablesignal quality (block 106). For example, this step may involvedetermining if the MIMO communications signal strength between theneighboring remote units 34 and the client device 36 exceeds apredefined MIMO communications signal quality threshold. If the signalquality of communications signals between the neighboring remote units34 and the client device 36 are determined to be of acceptable signalquality (block 106), the central unit 32 switches the cell bonding modefor the client device 36 by updating the dynamic cell antenna bondingtable 120 in FIG. 7 with the new remote unit(s) 34 assigned to beassociated or bonded with the client device 36 for MIMO communications(block 108). The client device 36 continues to communicate in the newcell-bonding mode and communications signal quality acceptability ischecked (block 110). If not acceptable, the process goes to block 104described above, in which the cell bonding mode may be switched for theclient device 36 and/or different remote units 34 associated or bondedwith the client device 36 employing either intra-cell antenna bonding orinter-cell antenna bonding depending on MIMO communications signalquality acceptability.

FIG. 9 illustrates exemplary MIMO communications performance of hybridintra-cell/inter-cell remote unit antenna bonding. FIG. 9 is anexemplary graph 140 illustrating exemplary MIMO communications serviceperformance in terms of percentage area of MIMO coverage for MIMOantenna 68 separations for three scenarios: (1) only intra-cell remoteunit antenna bonding; (2) only inter-cell remote unit antenna bonding;and (3) hybrid intra-cell/inter-cell remote unit antenna bonding in theMIMO DAS 30′ of FIG. 5. MIMO coverage curve 142 illustrates an exemplarypercentage area of MIMO coverage for a given MIMO antenna 68 separationdistance in the DAS 30′ in FIG. 5 when only intra-cell antenna bondingis employed. MIMO coverage curve 144 illustrates an exemplary percentagearea of MIMO coverage for a given MIMO antenna 68 separation distance inthe DAS 30′ in FIG. 5 when only inter-cell antenna bonding is employed.MIMO coverage curve 146 illustrates an exemplary percentage area of MIMOcoverage for a given MIMO antenna 68 separation distance in the DAS 30′in FIG. 5 when hybrid intra-cell/inter-cell antenna bonding is employed,including as provided in the embodiments described herein.

With continuing reference to FIG. 9, for inter-cell antenna bonding, aMIMO power imbalance threshold of 12 dB and condition number of 20 dB isassumed. For intra-cell antenna bonding, a typical MIMO condition numberof 60 dB is assumed. FIG. 9 shows that for extremely dense deployments(e.g., <10 m), intra-cell antenna bonding alone and inter-cell antennabonding alone could provide sufficient MIMO coverage. However, whenremote unit deployments with greater separation (e.g., >20 m) areconsidered, the proposed hybrid intra-cell/inter-cell antenna bondingaccording to the present embodiments may provide greater than 20% higherMIMO coverage than through only intra-cell antenna bonding or onlyinter-cell antenna bonding.

Note that although the MIMO distributed antenna systems described aboveallow for distribution of radio frequency (RF) communications signals,the MIMO distributed antenna systems described above are not limited todistribution of RF communications signals. Data communications signals,including digital data signals, for distributing data services couldalso be distributed in the MIMO DAS in lieu of, or in addition to, RFcommunications signals. Also note that while the MIMO DASs in FIG. 1described above include distribution of communications signals overoptical fiber, these MIMO DASs are not limited to distribution ofcommunications signals over optical fiber. Distribution media could alsoinclude, coaxial cables, twisted-pair conductors, wireless transmissionand reception, and combinations thereof. Also, any combination can beemployed that also involves optical fiber for portions of the DAS.

It may also be desired to provide high-speed wireless digital dataservice connectivity with remote units in the MIMO DASs disclosedherein. One example would be WiFi. WiFi was initially limited in datarate transfer to 12.24 Mb/s and is now provided at data transfer ratesof up to 54 Mb/s using WLAN frequencies of 2.4 GHz and 5.8 GHz. Whileinteresting for many applications, WiFi has proven to have too small abandwidth to support real time downloading of uncompressed highdefinition (HD) television signals to wireless client devices. Toincrease data transfer rates, the frequency of wireless signals could beincreased to provide larger channel bandwidth. For example, an extremelyhigh frequency in the range of 30 GHz to 300 GHz could be employed. Forexample, the sixty (60) GHz spectrum is an EHF that is an unlicensedspectrum by the Federal Communications Commission (FCC) and that couldbe employed to provide for larger channel bandwidths. However, highfrequency wireless signals are more easily attenuated or blocked fromtraveling through walls or other building structures where DASs areinstalled.

Thus, the embodiments disclosed herein can include distribution ofextremely high frequency (EHF) (i.e., approximately 30—approximately 300GHz), as a non-limiting example. The MIMO DASs disclosed herein can alsosupport provision of digital data services to wireless clients. The useof the EHF band allows for the use of channels having a higherbandwidth, which in turn allows more data intensive signals, such asuncompressed HD video to be communicated without substantial degradationto the quality of the video. As a non-limiting example, the DASsdisclosed herein may operate at approximately sixty (60) GHz withapproximately seven (7) GHz bandwidth channels to provide greaterbandwidth to digital data services. The DASs disclosed herein may bewell suited to be deployed in an indoor building or other facility fordelivering digital data services.

It may be desirable to provide MIMO DASs, according to the embodimentsdisclosed herein, that provide digital data services for client devices.For example, it may be desirable to provide digital data services toclient devices located within a DAS. Wired and wireless devices may belocated in the building infrastructures that are configured to accessdigital data services. Examples of digital data services include, butare not limited to, Ethernet, WLAN, WiMax, WiFi, DSL, and LTE, etc.Ethernet standards could be supported, including 100 Mb/s (i.e., fastEthernet) or Gigabit (Gb) Ethernet, or ten Gigabit (10G) Ethernet.Examples of digital data services include, wired and wireless servers,wireless access points (WAPs), gateways, desktop computers, hubs,switches, remote radio heads (RRHs), baseband units (BBUs), andfemtocells. A separate digital data services network can be provided toprovide digital data services to digital data client devices.

FIG. 10 is a schematic diagram representation of additional detailillustrating components that could be employed in any of the componentsor devices disclosed herein or in the MIMO distributed communicationsystems described herein, if adapted to execute instructions from anexemplary computer-readable medium to perform any of the functions orprocessing described herein. For example, the processes described inFIGS. 6A and 6B above could be provided as a result of executinginstructions from a computer-readable medium. Such component or devicemay include a computer system 150 within which a set of instructions forperforming any one or more of the location services discussed herein maybe executed. The computer system 150 may be connected (e.g., networked)to other machines in a LAN, an intranet, an extranet, or the Internet.While only a single device is illustrated, the term “device” shall alsobe taken to include any collection of devices that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein. The computer system150 may be a circuit or circuits included in an electronic board card,such as, a printed circuit board (PCB), a server, a personal computer, adesktop computer, a laptop computer, a personal digital assistant (PDA),a computing pad, a mobile device, or any other device, and mayrepresent, for example, a server or a user's computer.

The exemplary computer system 150 in this embodiment includes aprocessing device or processor 152, a main memory 154 (e.g., read-onlymemory (ROM), flash memory, dynamic random access memory (DRAM), such assynchronous DRAM (SDRAM), etc.), and a static memory 156 (e.g., flashmemory, static random access memory (SRAM), etc.), which may communicatewith each other via a data bus 158. Alternatively, the processing device152 may be connected to the main memory 154 and/or static memory 156directly or via some other connectivity means. The processing device 152may be a controller, and the main memory 154 or static memory 156 may beany type of memory.

The processing device 152 represents one or more general-purposeprocessing devices, such as a microprocessor, central processing unit,or the like. More particularly, the processing device 152 may be acomplex instruction set computing (CISC) microprocessor, a reducedinstruction set computing (RISC) microprocessor, a very long instructionword (VLIW) microprocessor, a processor implementing other instructionsets, or other processors implementing a combination of instructionsets. The processing device 152 is configured to execute processinglogic in instructions 160 for performing the operations and stepsdiscussed herein.

The computer system 150 may further include a network interface device162. The computer system 150 also may or may not include an input 164,configured to receive input and selections to be communicated to thecomputer system 150 when executing instructions. The computer system 150also may or may not include an output 166, including but not limited toa display, a video display unit (e.g., a liquid crystal display (LCD) ora cathode ray tube (CRT)), an alphanumeric input device (e.g., akeyboard), and/or a cursor control device (e.g., a mouse).

The computer system 150 may or may not include a data storage devicethat includes instructions 168 stored in a computer-readable medium 170.The instructions 168 may also reside, completely or at least partially,within the main memory 154 and/or within the processing device 152during execution thereof by the computer system 150, the main memory 154and the processing device 152 also constituting computer-readablemedium. The instructions 168 may further be transmitted or received overa network 172 via the network interface device 162.

While the computer-readable medium 170 is shown in an exemplaryembodiment to be a single medium, the term “computer-readable medium”should be taken to include a single medium or multiple media (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“computer-readable medium” shall also be taken to include any mediumthat is capable of storing, encoding, or carrying a set of instructionsfor execution by the processing device and that cause the processingdevice to perform any one or more of the methodologies of theembodiments disclosed herein. The term “computer-readable medium” shallaccordingly be taken to include, but not be limited to, solid-statememories, optical and magnetic medium, and carrier wave signals.

The steps of the embodiments disclosed herein may be formed by hardwarecomponents or may be embodied in machine-executable instructions, whichmay be used to cause a general-purpose or special-purpose processorprogrammed with the instructions to perform the steps. Alternatively,the steps may be performed by a combination of hardware and software.

The embodiments disclosed herein may be provided as a computer programproduct, or software, that may include a machine-readable medium (orcomputer-readable medium) having stored thereon instructions, which maybe used to program a computer system (or other electronic devices) toperform a process according to the embodiments disclosed herein. Amachine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer). For example, a machine-readable medium includes: amachine-readable storage medium (e.g., ROM, random access memory(“RAM”), a magnetic disk storage medium, an optical storage medium,flash memory devices, etc.); a machine-readable transmission medium(electrical, optical, acoustical, or other form of propagated signals(e.g., carrier waves, infrared signals, digital signals, etc.)); and thelike.

Unless specifically stated otherwise and as apparent from the previousdiscussion, discussions utilizing terms such as “processing,”“computing,” “determining,” “displaying,” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data and memoriesrepresented as physical (electronic) quantities within the computersystem's registers into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission, or display devices.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various systems may beused with programs in accordance with the teachings herein, or it mayprove convenient to construct more specialized apparatuses to performthe required method steps. The required structure for a variety of thesesystems will appear from the description above. In addition, theembodiments described herein are not described with reference to anyparticular programming language.

The logical blocks, modules, circuits, and algorithms described inconnection with the embodiments disclosed herein may be implemented aselectronic hardware, instructions stored in memory or in anothercomputer-readable medium and executed by a processor or other processingdevice, or combinations of both. The components of the DASs describedherein may be employed in any circuit, hardware component, integratedcircuit (IC), or IC chip, as examples. Memory disclosed herein may beany type and size of memory and may be configured to store any type ofinformation desired. To clearly illustrate this interchangeability,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.

The logical blocks, modules, and circuits described in connection withthe embodiments disclosed herein may be implemented or performed with aprocessor, a Digital Signal Processor (DSP), an Application SpecificIntegrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), orother programmable logic device, a discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. Furthermore, a controller may bea processor. A processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices.

The embodiments disclosed herein may be embodied in hardware and ininstructions that are stored in hardware, and may reside, for example,in RAM, flash memory, ROM, Electrically Programmable ROM (EPROM),Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk,a removable disk, a CD-ROM, or any other form of computer-readablemedium. An exemplary storage medium is coupled to the processor suchthat the processor can read information from, and write information to,the storage medium. In the alternative, the storage medium may beintegral to the processor. The processor and the storage medium mayreside in an ASIC, which may reside in a remote station. The processorand the storage medium may also reside as discrete components in aremote station, base station, or server.

The operations or steps described may be performed in numerous differentsequences other than the illustrated sequences. Furthermore, operationsdescribed in a single operational step may be performed in a number ofdifferent steps, and one or more operational steps may be combined.Information and signals may be represented using any of a variety oftechnologies and techniques. For example, data, instructions, commands,information, signals, bits, symbols, and chips, that may be referencedthroughout the above description, may be represented by voltages,currents, electromagnetic waves, magnetic fields, or particles, opticalfields or particles, or any combination thereof.

As used herein, it is intended that terms “fiber optic cables” and/or“optical fibers” include all types of single mode and multi-mode lightwaveguides, including one or more optical fibers that may be upcoated,colored, buffered, ribbonized, and/or have other organizing orprotective structure in a cable such as one or more tubes, strengthmembers, jackets, or the like.

Many modifications and other embodiments of the embodiments set forthherein will come to mind to one skilled in the art to which theembodiments pertain, and having the benefit of the teachings presentedin the forgoing descriptions and the associated drawings. Therefore, itis to be understood that the description and claims are not to belimited to the specific embodiments disclosed, and that modificationsand other embodiments are intended to be included within the scope ofthe appended claims.

What is claimed is:
 1. A distributed communications system, comprising:a central unit configured to: receive downlink communications signalsfor a multiple-input, multiple-output (MIMO) communications session froma signal source; distribute the received downlink communications signalsfor the MIMO communications session over at least one communicationsmedium to one or more remote units among a plurality of remote units;receive uplink communications signals for the MIMO communicationssession from one or more remote units among the plurality of remoteunits; distribute the received uplink communications signals for theMIMO communications session to the signal source; each remote unit amongthe plurality of remote units comprising: a first MIMO antenna; a secondMIMO antenna; each remote unit among the plurality of remote unitsconfigured to: receive the downlink communications signals for the MIMOcommunications session over the at least one communications medium fromthe central unit; distribute the received downlink communicationssignals for the MIMO communications session through the first MIMOantenna and the second MIMO antenna to at least one client device amongone or more client devices; receive the uplink communications signalsfor the MIMO communications session from the first MIMO antenna and thesecond MIMO antenna from at least one client device among the one ormore client devices; distribute the received uplink communicationssignals for the MIMO communications session over the at least onecommunications medium to the central unit; one of the central unit and aremote unit among the plurality of remote units is further configuredto: configure intra-cell antenna bonding for the MIMO communicationssession for the at least one client device in the remote unit with thefirst MIMO antenna and the second MIMO antenna in the remote unit in anintra-cell MIMO communications session; the remote unit among theplurality of remote units is further configured to: receive intra-cellantenna bonded MIMO communications signals from the at least one clientdevice at the first MIMO antenna and the second MIMO antenna in theremote unit in the intra-cell MIMO communications session; one of thecentral unit and a remote unit among the plurality of remote units isfurther configured to: determine if the received intra-cell antennabonded MIMO communications signals received by the first MIMO antennaand the second MIMO antenna of the remote unit from the at least oneclient device exceed a threshold MIMO communications signal quality; andif the received intra-cell antenna bonded MIMO communications signalsreceived by the first MIMO antenna and the second MIMO antenna of theremote unit from the at least one client device do not exceed thethreshold MIMO communications signal quality: the remote unit among theplurality of remote units is further configured to: receive MIMOcommunications signals from the at least one client device at anadjacent MIMO antenna of at least one adjacent remote unit to the remoteunit; one of the central unit and a remote unit among the plurality ofremote units is further configured to: determine if the received MIMOcommunications signals received by the adjacent MIMO antenna of the atleast one adjacent remote unit from the at least one client deviceexceed a threshold MIMO communications signal quality; and if thereceived MIMO communications signals received by the adjacent MIMOantenna of the at least one adjacent remote unit from the at least oneclient device exceed the threshold MIMO communications signal quality,configure inter-cell antenna bonding for inter-cell MIMO communicationsfor the at least one client device in the at least one adjacent remoteunit in the distributed communications system such that the at least oneclient device communicates with the adjacent MIMO antenna in the atleast one adjacent remote unit and at least one MIMO antenna among thefirst MIMO antenna and the second MIMO antenna in the remote unit in aninter-cell MIMO communications session.
 2. The distributedcommunications system of claim 1, wherein: the central unit furthercomprises: at least one electro-optical converter configured to convertthe received downlink communications signals for the MIMO communicationssession to received optical downlink communications signals; and atleast one optical-electro converter configured to convert the receiveduplink communications signals for the MIMO communications session toreceived electrical uplink communications signals; the central unit isconfigured to: distribute the received optical downlink communicationssignals for the MIMO communications session over the at least onecommunications medium to one or more remote units among the plurality ofremote units; and distribute the received electrical uplinkcommunications signals for the MIMO communications session to the signalsource; each remote unit among the plurality of remote units comprises:at least one optical-electro converter configured to convert thereceived optical downlink communications signals for the MIMOcommunications session to received electrical downlink communicationssignals; and at least one electro-optical converter configured toconvert the received uplink communications signals for the MIMOcommunications session from the first MIMO antenna and the second MIMOantenna from at least one client device among the one or more clientdevices, to received optical uplink communications signals; each of theplurality of remote units is configured to: distribute the receivedoptical uplink communications signals for the MIMO communicationssession over the at least one communications medium to the central unit;and distribute the received electrical downlink communications signalsfor the MIMO communications session through the first MIMO antenna andthe second MIMO antenna to at least one client device among the one ormore client devices.
 3. The distributed communications system of claim1, wherein: the central unit further comprises: at least one downlinkmixer configured to shift a frequency of the received downlinkcommunications signals from an original downlink frequency to a shifteddownlink frequency to provide frequency shifted downlink communicationssignals; and at least one uplink mixer configured to shift a frequencyof frequency shifted uplink communications signals from a shifted uplinkfrequency to an original uplink frequency of the uplink communicationssignals to provide the uplink communications signals; the central unitconfigured to distribute the frequency shifted downlink communicationssignals for the MIMO communications session over at least onecommunications medium to one or more remote units among the plurality ofremote units; and each of the plurality of remote units furthercomprises: at least one downlink mixer configured to shift the frequencyof the received frequency shifted downlink communications signals to theoriginal downlink frequency to provide the downlink communicationssignals; and at least one uplink mixer configured to shift the frequencyof the received uplink communications signals to the shifted uplinkfrequency to provide the frequency shifted uplink communicationssignals; each of the plurality of remote units configured to distributethe received shifted uplink communications signals for the MIMOcommunications session over the at least one communications medium tothe central unit.
 4. The distributed communications system of claim 1,wherein if the received MIMO communications signals at an adjacent MIMOantenna of the at least one adjacent remote unit from the at least oneclient device do not exceed the threshold MIMO communications signalquality, one of the central unit and a remote unit among the pluralityof remote units is further configured to retain the intra-cell antennabonding for intra-cell MIMO communications for the at least one clientdevice in the remote unit.
 5. The distributed communications system ofclaim 1, wherein: the remote unit among the plurality of remote units isfurther configured to: receive MIMO communications signals from the atleast one client device at the adjacent MIMO antenna of the at least oneadjacent remote unit and the at least one MIMO antenna among the firstMIMO antenna and the second MIMO antenna in the remote unit; one of thecentral unit and a remote unit among the plurality of remote units isfurther configured to: determine if the received MIMO communicationssignals by the adjacent MIMO antenna of the at least one adjacent remoteunit from the at least one client device exceed a threshold MIMOcommunications signal quality; and one of the central unit and a remoteunit among the plurality of remote units is further configured to: ifthe received MIMO communications signals by the adjacent MIMO antenna ofthe at least one adjacent remote unit from the at least one clientdevice exceed the threshold MIMO communications signal quality, retaininter-cell antenna bonding for inter-cell MIMO communications for the atleast one client device by the adjacent MIMO antenna of the at least oneadjacent remote unit and the at least one MIMO antenna among the firstMIMO antenna and the second MIMO antenna in the remote unit in the atleast one adjacent remote unit.
 6. The distributed communications systemof claim 1, wherein: the remote unit among the plurality of remote unitsis further configured to: receive MIMO communications signals from theat least one client device at the adjacent MIMO antenna of the at leastone adjacent remote unit and the at least one MIMO antenna among thefirst MIMO antenna and the second MIMO antenna in the remote unit; oneof the central unit and a remote unit among the plurality of remoteunits is further configured to: determine if the received MIMOcommunications signals by the adjacent MIMO antenna of the at least oneadjacent remote unit from the at least one client device exceed athreshold MIMO communications signal quality; and one of the centralunit and a remote unit among the plurality of remote units is furtherconfigured to: if the received MIMO communications signals by theadjacent MIMO antenna of the at least one adjacent remote unit from theat least one client device do not exceed the threshold MIMOcommunications signal quality, configure intra-cell antenna bonding forintra-cell MIMO communications for the at least one client device withthe first MIMO antenna and the second MIMO antenna in the remote unit.7. The distributed communications system of claim 1, wherein: the remoteunit among the plurality of remote units is further configured to:receive MIMO communications signals from the at least one client deviceat the adjacent MIMO antenna of at least one other adjacent remote unitto the at least one adjacent remote unit; one of the central unit and aremote unit among the plurality of remote units is further configuredto: determine if the received MIMO communications signals by theadjacent MIMO antenna of the at least one other adjacent remote unitfrom the at least one client device exceed a threshold MIMOcommunications signal quality; and one of the central unit and a remoteunit among the plurality of remote units is further configured to: ifthe received MIMO communications signals by the adjacent MIMO antenna ofthe at least one other adjacent remote unit from the at least one clientdevice exceed the threshold MIMO communications signal quality,configure inter-cell antenna bonding for MIMO communications for theclient device with the at least one other adjacent remote unit in theMIMO distributed communications system such that the client devicecommunicates with the adjacent MIMO antenna of the at least one otheradjacent remote unit and at least one adjacent MIMO antenna of the atleast one other adjacent remote unit in an inter-cell MIMOcommunications session.
 8. The distributed communications system ofclaim 1, wherein one of the central unit and a remote unit among theplurality of remote units is further configured to determine if thereceived intra-cell antenna bonded MIMO communications signals by thefirst MIMO antenna and the second MIMO antenna of the remote unit fromthe at least one client device exceed a threshold MIMO communicationssignal strength.
 9. The distributed communications system of claim 1,wherein one of the central unit and a remote unit among the plurality ofremote units is further configured to determine if the received MIMOcommunications signals at the at least one adjacent remote unit from theat least one client device exceed a threshold MIMO communications signalstrength.
 10. The distributed communications system of claim 1, whereinone of the central unit and a remote unit among the plurality of remoteunits is configured to store the intra-cell antenna bonding for theintra-cell MIMO communications for the at least one client device at theremote unit in a dynamic cell antenna bonding table.
 11. The distributedcommunications system of claim 1, wherein the one of the central unitand a remote unit among the plurality of remote units is configured tostore the inter-cell antenna bonding for the inter-cell MIMOcommunications for the at least one client device at the at least oneadjacent remote unit in a dynamic cell antenna bonding table, if thereceived MIMO communications signals by the adjacent MIMO antenna of theat least one adjacent remote unit from the at least one client deviceexceed the threshold MIMO communications signal quality.
 12. Thedistributed communications system of claim 1, wherein the one of thecentral unit and a remote unit among the plurality of remote units isfurther configured to identify the at least one adjacent remote unit tothe remote unit from a remote unit mapping table.
 13. The distributedcommunications system of claim 1, wherein the one of the central unitand a remote unit among the plurality of remote units comprises thecentral unit.
 14. The distributed communications system of claim 1,wherein the one of the central unit and a remote unit among theplurality of remote units comprises the remote unit.
 15. A distributedcommunications system, comprising: a central unit configured to: receivedownlink communications signals for a multiple-input, multiple-output(MIMO) communications session from a signal source; distribute thereceived downlink communications signals for the MIMO communicationssession over at least one communications medium to one or more remoteunits among a plurality of remote units; receive uplink communicationssignals for the MIMO communications session from one or more remoteunits among the plurality of remote units; distribute the receiveduplink communications signals for the MIMO communications session to thesignal source; each remote unit among the plurality of remote unitscomprising: a first MIMO antenna; a second MIMO antenna; each remoteunit among the plurality of remote units configured to: receive thedownlink communications signals for the MIMO communications session overthe at least one communications medium from the central unit; distributethe received downlink communications signals for the MIMO communicationssession through the first MIMO antenna and the second MIMO antenna to atleast one client device among one or more client devices; receive theuplink communications signals for the MIMO communications session fromthe first MIMO antenna and the second MIMO antenna from at least oneclient device among the one or more client devices; distribute thereceived uplink communications signals for the MIMO communicationssession over the at least one communications medium to the central unit;the central unit further configured to: configure intra-cell antennabonding for the MIMO communications session for the at least one clientdevice in a remote unit among the plurality of remote units with thefirst MIMO antenna and the second MIMO antenna in the remote unit in anintra-cell MIMO communications session; the remote unit among theplurality of remote units further configured to: receive intra-cellantenna bonded MIMO communications signals from the at least one clientdevice at the first MIMO antenna and the second MIMO antenna in theremote unit in the intra-cell MIMO communications session; the centralunit further configured to: determine if the received intra-cell antennabonded MIMO communications signals received by the first MIMO antennaand the second MIMO antenna of the remote unit from the at least oneclient device exceed a threshold MIMO communications signal quality; andif the received intra-cell antenna bonded MIMO communications signalsreceived by the first MIMO antenna and the second MIMO antenna of theremote unit from the at least one client device do not exceed thethreshold MIMO communications signal quality: the remote unit among theplurality of remote units further configured to: receive MIMOcommunications signals from the at least one client device at anadjacent MIMO antenna of at least one adjacent remote unit to the remoteunit; the central unit further configured to: determine if the receivedMIMO communications signals received by the adjacent MIMO antenna of theat least one adjacent remote unit from the at least one client deviceexceed a threshold MIMO communications signal quality; and if thereceived MIMO communications signals received by the adjacent MIMOantenna of the at least one adjacent remote unit from the at least oneclient device exceed the threshold MIMO communications signal quality,configure inter-cell antenna bonding for inter-cell MIMO communicationsfor the at least one client device in the at least one adjacent remoteunit in the distributed communications system such that the at least oneclient devices communicates with the adjacent MIMO antenna in the atleast one adjacent remote unit and at least one MIMO antenna among thefirst MIMO antenna and the second MIMO antenna in the remote unit in aninter-cell MIMO communications session.
 16. A distributed communicationssystem, comprising: a central unit configured to: receive downlinkcommunications signals for a multiple-input, multiple-output (MIMO)communications session from a signal source; distribute the receiveddownlink communications signals for the MIMO communications session overat least one communications medium to one or more remote units among aplurality of remote units; receive uplink communications signals for theMIMO communications session from one or more remote units among theplurality of remote units; distribute the received uplink communicationssignals for the MIMO communications session to the signal source; eachremote unit among the plurality of remote units comprising: a first MIMOantenna; a second MIMO antenna; each remote unit among the plurality ofremote units configured to: receive the downlink communications signalsfor the MIMO communications session over the at least one communicationsmedium from the central unit; distribute the received downlinkcommunications signals for the MIMO communications session through thefirst MIMO antenna and the second MIMO antenna to at least one clientdevice among one or more client devices; receive the uplinkcommunications signals for the MIMO communications session from thefirst MIMO antenna and the second MIMO antenna from at least one clientdevice among the one or more client devices; distribute the receiveduplink communications signals for the MIMO communications session overthe at least one communications medium to the central unit; the centralunit further configured to: configure intra-cell antenna bonding for theMIMO communications session for the at least one client device in aremote unit among the plurality of remote units with the first MIMOantenna and the second MIMO antenna in the remote unit in an intra-cellMIMO communications session; and the remote unit among the plurality ofremote units further configured to: receive intra-cell antenna bondedMIMO communications signals from the at least one client device at thefirst MIMO antenna and the second MIMO antenna in the remote unit in theintra-cell MIMO communications session; and determine if the receivedintra-cell antenna bonded MIMO communications signals received by thefirst MIMO antenna and the second MIMO antenna of the remote unit fromthe at least one client device exceed a threshold MIMO communicationssignal quality; and if the received intra-cell antenna bonded MIMOcommunications signals received by the first MIMO antenna and the secondMIMO antenna of the remote unit from the at least one client device donot exceed the threshold MIMO communications signal quality: the remoteunit among the plurality of remote units further configured to: receiveMIMO communications signals from the at least one client device at anadjacent MIMO antenna of at least one adjacent remote unit to the remoteunit; and determine if the received MIMO communications signals receivedby the adjacent MIMO antenna of the at least one adjacent remote unitfrom the at least one client device exceed a threshold MIMOcommunications signal quality; and the central unit further configuredto: if the received MIMO communications signals received by the adjacentMIMO antenna of the at least one adjacent remote unit from the at leastone client device exceed the threshold MIMO communications signalquality, configure inter-cell antenna bonding for inter-cell MIMOcommunications for the at least one client device in the at least oneadjacent remote unit in the distributed communications system such thatthe at least one client device communicates with the adjacent MIMOantenna in the at least one adjacent remote unit and at least one MIMOantenna among the first MIMO antenna and the second MIMO antenna in theremote unit in an inter-cell MIMO communications session.